Method of manufacturing high pressure hose coupling

ABSTRACT

A coupling for high pressure hose in which an annular portion of an inner member is secured to a bore of an outer member along two separate circumferential regions. In the method of making the coupling the inner member is placed in a central recess in an anvil which has a frusto-conical annular upper end face that is engaged by an end wall of the outer member. A mandrel is forced into the bore of the inner member to deform its wall into engagement with the wall of the bore of the sleeve both at the end of the mandrel and at the end of the anvil.

Unite States Patent [1 1 Brand Nov. 6, 1973 METHOD OF MANUFACTURING HIGHPRESSURE HosE COUPLING [75] Inventor: KarlBrand, Ebern, Germany [73]Assignee: Kugelfischer Georg Schafer & Co.,

Schweinfurt, Germany 22 Filed: Jan. 31, 1972 [21] Appl. No.: 222,410

Related US. Application Data [62] Division of Ser. No. 113,839, Feb. 9,1971.

[30] Foreign Application Priority Data 2,433,425 12/1947 Burcklc285/3824 X 2,808,643 10/1957 Weatherhead 29/508 3,433,505 3/1969Weathcrhead 285/256 X 3,525,542 8/1970 Bclart et al. 285/256 3,584,9036/1971 Pritchard 29/523 X 3,699,625 Spencer 29/523 X PrimaryExaminerCharlie T. Moon AttorneyStevens et al.

[ 5 7] ABSTRACT A coupling for high pressure hose in which an annularportion of an inner member is secured to a bore of an outer member alongtwo separate circumferential regions. 1n the method of making thecoupling the inner member is placed in a central recess in an anvilwhich has a frusto-conical annular upper end face that is engaged by anend wall of the outer member. A mandrel is forced into the bore of theinner member to deform its wall into engagement with the wall of thebore of the sleeve both at the end of the mandrel and at the end of theanvil.

5 Claims, 8 Drawing Figures PAIENIEDnuv e um SHEET 10F 2 FIG. 5

FIG. 6

This is a division of application Ser. No. l.l3,839, filed Feb. 9, I971.

The present invention relates to an end coupling for high pressurehoses, for example for hoses for use in hydraulic brakes for vehicles,the end coupling being of smooth uniform length of tubing, has afrusto-conical end face which engages against the shoulder between theportions of larger and smaller diameter of the bore the type having aninner member that enters the end of the hose proper and an outer memberwhich is provided at one end with internal or external means forengagement with a hydraulic cylinder or other component, the other endof the outer member being in the form of a skirt which is capable ofbeing deformed inwards to grip the hose material and clamp it betweenthe outer member and the inner member within the hose.

The present invention relates in particular to the construction of theend coupling so that its inner member and outer member are sealedtogether in a fluid-tight manner and the invention also relates to amethod of assembling the end coupling.

Various means and methods are already known for securing together theinner and the outer members of a hose coupling in a fluid-tight manneragainst the high pressure developed in the hose in question. Forexample, it is known for the inner member to have an external surfacewhich diverges towards that end which is furthest from the main body ofthe hose in the assembled structure, and for the outer member to have acorrespondingly tapered internal bore; the inner member being forcedinto the outer member from the screwthreaded end of the latter. In analternative construction, the bore of the outer member tapersconvergently towards its screw-threaded end with a shoulder at thesmaller end of the conical bore joining this bore to a further bore ofreduced diameter. The inner member, of which the external surface taperstowards the end furthest from the body of the hose, is forced into theouter member from the larger end of the latter until it engages againstthe shoulder. In yet another construction the inner member is in theform of a substantially plain cylindrical tube initially and the outermember has an internal bore which is conical at that end which istowards the main body of the hose and tapers towards the screw-threadedend, to meet a portion of smaller diameter at an annular shoulder. Thetubular inner member is expanded to engage against the conical wall ofthe bore of the outer member. Alternatively, again with an inner memberwhich is initially a plain tubular form, the bore of the outer member islargely of plain cylindrical form but that end of the bore which istowards the main body of the hose tapers convergently towards this end.In the first case the inner member is forced axially into the outermember from the hose end of the outer member, whilst in the second casethe inner member is forced axially into the outer member from thescrew-threaded end of the latter. in this last case, in place of theconical portion of the bore of the outer member, there could simply be astepped portion against which the inner member is forced. Finally, it isalso known to have an inner member of rigid form and an outer memberwhich is capable of plastic deformation and has a bore made up of aportion of smaller diameter nearest the screw-threaded end of the outermember and a portion of larger diameter towards the other end; the innermember, which is forged from a in the outer member and then the innermember is peened over or inert-gas welded at its point of emergence fromthe bore of the outer member.

Higher and higher standards are constantly being set for the degree offluid-tightness and security between the components of hose couplings,especially those intended for use on hydraulic brake hoses for vehicles.The fluid-tightness between couplings and hoses is quality-tested byobserving the increase in volume when the pressure of the hydraulicmedium present in the hose under test is increased in successive steps,a longer and longer time interval being interposed between successiveincrease in pressure so that any possible loss of fluid is made morenoticeable. Moreover, no expansion or formation of bulges must beobservable in the wall of the hose and, more important, no hydraulicfluid must penetrate into the material of the hose, for example bypartial leakage at the end in the coupling.

Penetration of hydraulic fluid into the body of the hose, for example atthe end, must be avoided as it results in damage to the strength of thefabric reinforcement in the hose. It has been found that with many ofthe known hose couplings the connection between the inner member and theouter member of the coupling allows a seepage of the hydraulic fluid tooccur after several months of use. The stresses set up in the materialof the coupling on initial assembly tend to disappear with time,especially in view of the limited wall thickness of the components ofthe coupling. Where an attempt is made to obtain additional security byuse of welding, there is danger of weld cracks being formed, resultingin consequent sealing failures under the continuously varying pressureloadings to which the coupling is subjected. In the last of the knownmethods of assembly mentioned above, in which the, rigid inner memberhas a frusto-conical end face engaging a shoulder in the bore of theouter member, there is the further disadvantage that inevitabletolerances in the bore size of the outer member and in the externaldiameter of the inner member mean that complete sealing between thesetwo components is not always achieved, and the same is true because oflack of roundness of the frustoconical face as a consequence of themanufacturing methods. Thus, sealing failures can be expected at thecircumferential sealing point between the end face of the inner memberand the shoulder in the bore of the outer member. The possibility hastherefore been considered of taking additional steps in the form offorging or swaging or welding of the inner member but even this does notallow complete elimination of seepage of fluid at very high pressuresand over long periods of time.

It is therefore an object of the present invention to provide a hosecoupling, and a method of assembling it, which is suitable for use onhigh pressure hoses, for example for vehicle braking systems, andcapable of maintaining its fluid-tightness at pressures up to as much as400 or 500 atmospheres.

This is achieved in a high pressure hose coupling of the kind outlinedabove in that, between the inner member portion of the coupling and theouter member there are provided at least two separate circumferentiallyextending sealing regions produced by deformation. Preferably the secondcircumferential sealing region is in the form of an annular constrictionin the wall of the inner member, engaged by an inner edge, pressing intothe inner member, of the bore of the outer member near thescrew-threaded end of the latter. In addition to this region or insteadof it, there may also be a bulge or portion of increased cross-sectionin that region of the inner member which is furthest from the main bodyof the hose, this bulge being pressed against the wall of anincreased-diameter portion of the bore of the outer member near thescrew-threaded end of the outer member, the inner member being forcedinto this bore.

Also, the invention concerns a method for manufacturing a coupling forhigh pressure hoses of the kind comprising an inner member, which isinserted into the bore in an outer member, in which, as the inner memberis forced into the outer member the inner member is deformed against thewall of the bore of the outer member to form an additionalcircumferential sealing region. Preferably the outer member, with theinner member already in place in it, is set up on an anvil which has acentral bore to receive the inner member and has at its upper end a flatfrusto-conical annular bearing face for the outer member, this facebeing concave towards the central bore, and then the outer member isforced downwards against the anvil so that the frusto-conical facedeforms the material of the edge of the outer member inwards against thewall of the inner member, forming a constriction in the latter, whilstin addition a ball-like mandrel is forced at least partially into thebore of the inner member to deform the wall thereof laterally outwardsagainst the wall of the bore of the outer member. The bore of thatportion of the outer member which is engaged by the inner member may beof uniform diameter or it may have a portion of increased diameter nearthe screw-threaded end.

The means for accomplishing the foregoing objects and other advantages,which will be apparent to those skilled in the art, are set forth in thefollowing specification and claims, and are illustrated in theaccompanying drawings dealing with a basic embodiment of the presentinvention. Reference is made now to the drawings in which:

FIG. I is an external elevation of a hose coupling ac-' cording to theinvention, mounted on the end of a length of hose;

FIG. 2 is a largely sectioned side view of one embodiment of thecoupling according to the invention, during its assembly on an anvil;

FIG. 3 is a view similar to FIG. 2, showing an alternative embodiment ofthe coupling according to the invention, during its assembly on ananvil;

FIG. 4 shows, on an enlarged scale, the portion of an assembled couplingnoted by IV in FIG. 2;

FIG. 5 shows, on an enlarged scale, the portion of an assembled couplingnoted by V in FIG. 2;

FIG. 6 shows, on an enlarged scale, the portion of an assembled couplingnoted by VI in FIG. 2;

FIG. 7 is an enlarged detailed vertical section of the coupling duringassembly; and

FIG. 8 is an enlarged detailed vertical section of the completedcoupling before dismounting from the anvil.

Referring first to FIG. 1, the end of a flexible high pressure hose 1 isreceived in an end coupling 2 by which it can be connected in afluid-tight manner to a component such as a hydraulic cylinder or valve,this coupling 2 being provided for this purpose with connection means 3.It will be understood that instead of the internal thread shown, anexternal screw-thread or even some other form of connection means couldbe provided. An enlarged intermediate portion of the length of thefitting has an external hexagonal shape to allow it to be screwed to thecomponent by means of a wrench. I

The coupling comprises an inner member 6 of basically plain tubularform, received in an outer member 4 on which the hexagonal portion isformed and of which one end carries the connecting means 3. The otherend of the outer member forms the skirt which is capable of radialinward deformation by an appropriate tool in a manner not shown, so asto secure in a fluidtight manner the end of the hose 1 between the innermember 6 and the skirt of the outer member 4.

As shown in FIG. 2, to assemble the inner member and the outer membertogether, the inner member 6 is first inserted in the bore 5 of theouter member (this bore being of uniform diameter in the version shownin FIG. 2) and then the outer member is fitted over an upstandingportion of an anvil 7, which has an axial bore 8 to receive the lowerend of the inner member 6. The upper end of the anvil is in the form ofa frusto-conical concave surface 9. When a tool 10 is used to force theouter member downwards onto the anvil, this frustoconical surface, asshown in FIGS. 7 and 8, forces the material 16 of the outer member atthe shoulder 14 between the bore 5 and the enlarged counter bore 15,that is shaped to receive the end of the hose, radially inwards todeform the wall of the inner member at this point forming a slightconstriction and at the same time forming a very effectivecircumferentially extending sealing region between the inner member 6and the outer member 4.

In addition, the tool 10 forms a guide for a mandrel 11 having a ballhead 12 that is forced downwards into the bore 5 of the inner member 6,deforming the wall thereof laterally outwards tightly into engagementwith the wall of the bore 5 of the outer member, at the same timereducing the wall thickness of the inner member 6. This portion 6 ofreduced diameter is most clearly shown in FIGS. 4, 7 and 8 andconstitutes a second circumferentially extending sealing region betweenthe outer member and the inner member. Normally the mandrel 11 can beforced downwards first to form this seal, after which the tool 10 isstruck to produce the other sealing region at the shoulder 14. However,it will be understood that these steps may be performed in the reverseorder or simultaneously.

The hose end fitting shown in FIG. 3 differs from that of FIG. 2 only inthat the bore 5 of the central region of the outer member 4, instead ofbeing of uniform diameter, has in it a step 17 of increased diametertowards the end having connection means 3. The ball head 12 on the endof the mandrel ll deforms the wall of the inner member 6 outwards to fitthis enlarged diameter, resulting in an enlarged portion 6" of the innermember 6 that cooperates with the step 17 or shoulder between theportions of smaller and larger diameter 5 and 5, respectively, of thebore in the outer member, thus forming a further circumferentiallyextending sealing region between the outer member 4 and the inner member6 at this point.

The outer member 4 and the inner member 6, as well as the hose 1 itself,can be made of the usual materials employed for these components. Forexample, the

inner member 6 can be of brass or steel tube and the outer member 4 canbe formed of free-cutting steel. The anvil 7, the tool 10 and themandrel 11 with its head 12, are preferably made of hardened steel.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than the foregoing description, and all changeswhich come within the meaning and range of equivalency of the claims aretherefore to be embraced therein.

What is claimed:

1. A method of manufacturing a hose coupling of the type comprising aninner member adapted to enter the bore of a hose and an outer memberhaving a bore to receive said inner member therein, a skirt adapted toextend over the external surface of the hose and to be deformed inwardsto grip the material of the hose and coupling means on the end oppositethe skirt, comprising the steps of mounting said inner member in thebore of said outer member, forming a first circumferential sealingregion between the inner member and the outer member by deforming theinner member outwards against the wall of said bore and, at a pointspaced from said first region, forming a second circumferential sealingby forming an annular constriction in said inner member and deformingsaid outer member inwardly into said constriction.

2. A method according to claim 1, wherein said first circumferentialsealing is formed by forcing a mandrel into the bore of the inner memberto deform the wall thereof outwards into tight engagement with the boreof the outer member.

3. A method according to claim 2, in which the bore of the outer memberthat receives the inner member is of uniform diameter and wherein themandrel is forced into the bore of the inner member to locally reducethe wall thickness of the inner member while forcing it outwardly intocircumferential sealing contact with said bore of the outer member.

4. A method according to claim 2, in which the bore of the outer memberthatreceives the inner member has portions of different diameters with aportion of larger diameter near that end which is remote from the bore,wherein the mandrel is forced into the bore of the inner member toenlarge the diameter thereof locally to engage the portion of largerdiameter of the bore of the outer member thereby producing acircumferential sealing region at the shoulder between the portions ofsmaller and larger diameter of said bore.

5. A method according to claim 1, wherein said second circumferentialsealing is formed by mounting the outer member with said inner membermounted in its bore on an anvil having a central recess receiving theinner member therein and a frusto-conical annular face that is engagedby an end wall on the outer member, and pressing the outer memberagainst said frustoconical face to deform an edge portion of said outermember surrounding the bore inwards into the external surface of theinner member to deform the wall thereof to form an annular constrictionin the inner member and said second sealing therebetween.

1. A method of manufacturing a hose coupling of the type comprising aninner member adapted to enter the bore of a hose and an outer memberhaving a bore to receive said inner member therein, a skirt adapted toextenD over the external surface of the hose and to be deformed inwardsto grip the material of the hose and coupling means on the end oppositethe skirt, comprising the steps of mounting said inner member in thebore of said outer member, forming a first circumferential sealingregion between the inner member and the outer member by deforming theinner member outwards against the wall of said bore and, at a pointspaced from said first region, forming a second circumferential sealingby forming an annular constriction in said inner member and deformingsaid outer member inwardly into said constriction.
 2. A method accordingto claim 1, wherein said first circumferential sealing is formed byforcing a mandrel into the bore of the inner member to deform the wallthereof outwards into tight engagement with the bore of the outermember.
 3. A method according to claim 2, in which the bore of the outermember that receives the inner member is of uniform diameter and whereinthe mandrel is forced into the bore of the inner member to locallyreduce the wall thickness of the inner member while forcing it outwardlyinto circumferential sealing contact with said bore of the outer member.4. A method according to claim 2, in which the bore of the outer memberthat receives the inner member has portions of different diameters witha portion of larger diameter near that end which is remote from thebore, wherein the mandrel is forced into the bore of the inner member toenlarge the diameter thereof locally to engage the portion of largerdiameter of the bore of the outer member thereby producing acircumferential sealing region at the shoulder between the portions ofsmaller and larger diameter of said bore.
 5. A method according to claim1, wherein said second circumferential sealing is formed by mounting theouter member with said inner member mounted in its bore on an anvilhaving a central recess receiving the inner member therein and afrusto-conical annular face that is engaged by an end wall on the outermember, and pressing the outer member against said frusto-conical faceto deform an edge portion of said outer member surrounding the boreinwards into the external surface of the inner member to deform the wallthereof to form an annular constriction in the inner member and saidsecond sealing therebetween.